Navigating Pharmacogenomic Testing in Practice: Who to Test and When to Test

There is increasing attention on the clinical utility and value of pharmacogenetic (PGx) testing to individualize medication management. Most clinical practice guidelines from medical professional societies do not recommend routine PGx testing, with a few key exceptions. Inconsistent recommendations across clinical practice guidelines, FDA product labeling, and payer reimbursement policies have hampered widespread adoption of testing. Multiple resources exist to aid in the adoption and use of actionable PGx test results in clinical practice; however, most of these resources do not provide guidance on who should receive PGx testing and when-a critical question the clinical community continues to struggle with. There are multiple considerations when answering this question beyond the clinical validity of the drug-gene interaction itself, such as the actionable result frequency, severity of the adverse clinical outcome, predictive power of the PGx test, suitability of alternative treatments, cost, and turnaround time of test results. This perspective discusses these considerations and models for testing including preemptive screening, pretreatment testing, and reactive testing, highlighting advantages and disadvantages of each approach. The authors provide their perspectives on identifying candidates for PGx testing in the current real-world environment and how that differs from a clinically ideal scenario.